Reactivity of Paramagnetic FeII-Bis(amidinate) Complexes

• Published in: European Journal of Inorganic Chemistry Vol. 2011; no. 1; pp. 91 - 100
• Main Authors: Jellema, Erica, Sciarone, Timo J. J., Navarrete, Noa M., Hettinga, Marten J., Meetsma, Auke, Hessen, Bart
• Format: Book Review
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-01-2011; WILEY‐VCH Verlag
• Subjects: Carb­onylation; Iron; Lewis bases; Magnetic properties; N ligands
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201000717

Synthesis and characterisation of ether adducts of bis(amidinate) FeII complexes are described [amidinate = 2,6‐iPr2C6H3–NC(Ph)N–Ph]. The isolation of these five‐coordinate complexes contrasts with the homoleptic bis(amidinate) Fe complexes obtained previously with the sterically more demanding amidinate ligands 2,6‐iPr2C6H3–NC(Ph)N–Ar (Ar = 2,6‐iPr2C6H3, 2,6‐Me2C6H3) The more accessible ether adducts show enhanced reactivity towards Lewis bases and towards the π‐acid carbon monoxide. Reaction with excess amounts of CO results in carbonyl insertion into the Fe–N bonds, thereby giving rise to a diamagnetic bis(CO) adduct supported by two carbamoyl ligands.
The influence of sterically demanding aryl substituents on the nitrogen atoms of amidinate ligands was investigated in paramagnetic bis(amidinate) FeII complexes. Reactivity towards Lewis bases and CO is almost completely suppressed with the most bulky ligand. Gradual restoration of reactivity is observed with sterically less demanding ligands.